High pressure boilers are commonly used in industry for producing steam to be used in operating machinery or in other manufacturing applications, and also for heating buildings. During the hours when manufacturing processes are shut down, the high pressure boilers may be operated as low pressure boilers to heat the buildings. Due to the operating characteristics and potential hazards attendant to the operation of a high pressure boiler, in some areas safety requirements dictate the presence of a trained certified boiler operator during operation of a high pressure boiler. Since low pressure boilers, i.e., boilers operating at less than 15 psi, are not accompanied by the same dangers, low pressure boilers do not require an operator to be in attendance.
In those cases where a high pressure boiler is employed for heat as well as in manufacturing operations, when the manufacturing equipment is not in operation and the boiler is not required to operate at high pressure and is used only as a low pressure boiler to maintain heating of a building, in some areas it is still necessary that the operator be present to insure the safe operation of the boiler. While the boiler pressure can be reduced during low load conditions such that the boiler functions as a low pressure boiler, since these boilers are not equipped with relief valves operable during low pressure operation of the boiler and since a malfunction of the boiler could result in the same dangers incident to operation as a high pressure boiler, it is still necessary in some areas to have a skilled operator present. For example, on weekends, manufacturing equipment may be shut down and the boiler may be needed only to heat the building. For heating purposes, low pressure operation of the boiler would be sufficient. However, because a failure of a high pressure boiler can be substantially more dangerous than that of a low pressure boiler, a trained operator must supervise operation of the high pressure boiler. This results in substantial labor costs which would not be incurred if the boiler could be operated as a low pressure boiler during those time periods.